U.S. patent application number 14/119070 was filed with the patent office on 2014-04-03 for non-contact power reception device and vehicle including the same, non-contact power transmission device, and non-contact power transfer system.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Shinji Ichikawa. Invention is credited to Shinji Ichikawa.
Application Number | 20140091641 14/119070 |
Document ID | / |
Family ID | 47258629 |
Filed Date | 2014-04-03 |
United States Patent
Application |
20140091641 |
Kind Code |
A1 |
Ichikawa; Shinji |
April 3, 2014 |
NON-CONTACT POWER RECEPTION DEVICE AND VEHICLE INCLUDING THE SAME,
NON-CONTACT POWER TRANSMISSION DEVICE, AND NON-CONTACT POWER
TRANSFER SYSTEM
Abstract
AC power having a power transmission frequency is transmitted
from a resonant coil in a power transmission device to a resonant
coil in a power reception device. Moreover, communication is
conducted between a communication device in the power transmission
device and a communication device in the power reception device
through wireless radio wave having a communication frequency. The
power transmission frequency and the communication frequency are
determined in such a way that the relationship between the power
transmission frequency and the communication frequency is a
non-integer multiple.
Inventors: |
Ichikawa; Shinji;
(Toyota-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ichikawa; Shinji |
Toyota-shi |
|
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi-ken
JP
|
Family ID: |
47258629 |
Appl. No.: |
14/119070 |
Filed: |
June 3, 2011 |
PCT Filed: |
June 3, 2011 |
PCT NO: |
PCT/JP2011/062818 |
371 Date: |
November 20, 2013 |
Current U.S.
Class: |
307/104 |
Current CPC
Class: |
B60L 53/38 20190201;
H02J 50/80 20160201; B60L 53/65 20190201; Y02T 10/7072 20130101;
B60L 53/122 20190201; Y02T 10/70 20130101; B60L 2210/30 20130101;
H02J 50/12 20160201; B60L 53/36 20190201; B60L 50/51 20190201; B60L
2270/147 20130101; B60L 2210/10 20130101; Y02T 10/72 20130101; Y02T
90/16 20130101; Y02T 90/14 20130101; B60L 2210/40 20130101; B60L
2240/529 20130101; Y04S 30/14 20130101; Y02T 90/12 20130101; Y02T
90/167 20130101; H02J 50/90 20160201; H02J 7/025 20130101; B60L
2240/527 20130101 |
Class at
Publication: |
307/104 |
International
Class: |
H02J 17/00 20060101
H02J017/00 |
Claims
1. A non-contact power reception device configured to receive in a
non-contact manner power transmitted from a power transmission
device, comprising: a power reception unit configured to receive in
a non-contact manner AC power transmitted from said power
transmission device at a first frequency; and a communication
device configured to conduct wireless communication with said power
transmission device through radio wave having a second frequency,
said first frequency and said second frequency being determined in
such a way that the relationship between said first frequency and
said second frequency is a non-integer multiple.
2. The non-contact power reception device according to claim 1,
wherein said power reception unit receives in a non-contact manner
said AC power transmitted from a power transmission unit in said
power transmission device through resonance with said power
transmission unit via an electromagnetic field.
3. The non-contact power reception device according to claim 1,
wherein said second frequency is determined to be higher than said
first frequency.
4. The non-contact power reception device according to claim 1,
wherein said first frequency is determined on the basis of a
transfer status of said AC power, and said second frequency is
determined in such a way that the relationship between the
determined first frequency and said second frequency is a
non-integer multiple.
5. The non-contact power reception device according to claim 1,
wherein said second frequency is determined on the basis of a
communication status with said power transmission device, and said
first frequency is determined on the basis of a transfer status of
said AC power in such a range that the relationship between the
determined second frequency and said first frequency is a
non-integer multiple.
6. The non-contact power reception device according to claim 1,
further comprising a modification unit configured to modify said
second frequency in such a way that the relationship between said
first frequency and said second frequency is a non-integer
multiple.
7. The non-contact power reception device according to claim 1,
further comprising a modification unit configured to modify said
first frequency in such a way that the relationship between said
first frequency and said second frequency is a non-integer
multiple.
8. The non-contact power reception device according to claim 1,
wherein said communication device is capable of selecting one from
a plurality of communication frequencies to conduct the wireless
communication with said power transmission device, and selects a
communication frequency which is a non-integer multiple of said
first frequency from said plurality of communication frequencies as
said second frequency to conduct the wireless communication with
said power transmission device.
9. A vehicle comprising the non-contact power reception device
according to claim 1.
10. A non-contact power transmission device configured to transmit
in a non-contact manner power to a power reception device,
comprising: a power supply unit configured to generate AC power
having a first frequency; a power transmission unit configured to
transmit in a non-contact manner said AC power generated by said
power supply unit to said power reception device; and a
communication device configured to conduct wireless communication
with said power reception device through radio wave having a second
frequency, said first frequency and said second frequency being
determined in such a way that the relationship between said first
frequency and said second frequency is a non-integer multiple.
11. The non-contact power transmission device according to claim
10, wherein said power transmission unit transmits in a non-contact
manner said AC power to a power reception unit in said power
reception device through resonance with said power reception unit
via an electromagnetic field.
12. The non-contact power transmission device according to claim
10, wherein said second frequency is determined to be higher than
said first frequency.
13. The non-contact power transmission device according to claim
10, wherein said first frequency is determined on the basis of a
transfer status of said AC power, and said second frequency is
determined in such a way that the relationship between the
determined first frequency and said second frequency is a
non-integer multiple.
14. The non-contact power transmission device according to claim
10, wherein said second frequency is determined on the basis of a
communication status with said power reception device, and said
first frequency is determined on the basis of a transfer status of
said AC power in such a range that the relationship between the
determined second frequency and said first frequency is a
non-integer multiple.
15. The non-contact power transmission device according to claim
10, further comprising a modification unit configured to modify
said second frequency in such a way that the relationship between
said first frequency and said second frequency is a non-integer
multiple.
16. The non-contact power transmission device according to claim
10, farther comprising a modification unit configured to modify
said first frequency in such a way that the relationship between
said first frequency and said second frequency is a non-integer
multiple.
17. The non-contact power transmission device according to claim
10, wherein said communication device is capable of selecting one
from a plurality of communication frequencies to conduct the
wireless communication with said power reception device, and
selects a communication frequency which is a non-integer multiple
of said first frequency from said plurality of communication
frequencies as said second frequency to conduct the wireless
communication with said power reception device.
18. A non-contact power transfer system configured to transfer in a
non-contact manner power from a power transmission device to a
power reception device, said power transmission device including: a
power supply unit configured to generate AC power having a first
frequency; a power transmission unit configured to transmit in a
non-contact manner said AC power generated by said power supply
unit to said power reception device; and a first communication
device configured to conduct wireless communication with said power
reception device through radio wave having a second frequency, said
power reception device including: a power reception unit configured
to receive in a non-contact manner said AC power transmitted from
said power transmission unit; and a second communication device
configured to conduct wireless communication with said power
transmission device through radio wave having said second
frequency, said first frequency and said second frequency being
determined in such a way that the relationship between said first
frequency and said second frequency is a non-integer multiple.
19. The non-contact power transfer system according to claim 18,
wherein said power transmission unit transmits in a non-contact
manner said AC power to said power reception unit through resonance
with said power reception unit via an electromagnetic field, and
said power reception unit receives in a non-contact manner said AC
power transmitted from said power transmission unit through
resonance with said power transmission unit via an electromagnetic
field.
20. The non-contact power transfer system according to claim 18,
wherein said second frequency is determined to be higher than said
first frequency.
21. The non-contact power transfer system according to claim 18,
further comprising a control unit configured to adjust said first
frequency on the basis of a transfer status of said AC power and
modify said second frequency in such a way that the relationship
between the adjusted first frequency and said second frequency is a
non-integer multiple.
22. The non-contact power transfer system according to claim 18,
further comprising a control unit configured to determine said
second frequency on the basis of a communication status with said
power transmission device, and after the determination of said
second frequency, adjust said first frequency on the basis of a
transfer status of said AC power in such a range that the
relationship between said first frequency and said second frequency
is a non-integer multiple.
23. The non-contact power transfer system according to claim 18,
wherein said first and second communication devices are capable of
selecting one from a plurality of communication frequencies to
conduct the wireless communication with each other, and select a
communication frequency which is a non-integer multiple of said
first frequency from said plurality of communication frequencies as
said second frequency to conduct the wireless communication with
each other.
Description
TECHNICAL FIELD
[0001] The present invention relates to a non-contact power
reception device and a vehicle including the same, a non-contact
power transmission device, and a non-contact power transfer system,
and in particular, relates to a non-contact power reception device
configured to conduct power transfer wirelessly and a vehicle
including the same, a non-contact power transmission device, and a
non-contact power transfer system.
BACKGROUND ART
[0002] Japanese Patent Laying-Open No. 2002-209343 (PTD 1)
discloses a system capable of transferring power in a non-contact
manner from an interrogator to a transponder so as to charge a
capacitor in the transponder. In the system, data communication is
conducted between the transponder and the interrogator through an
electromagnetic wave having a first frequency. Meanwhile, an
electromagnetic wave having a second frequency lower than the first
frequency is output from the interrogator to electromagnetically
couple a charging antenna disposed in each of the interrogator and
the transponder so as to charge the capacitor in the transponder
(see PTD 1).
CITATION LIST
Patent Document
[0003] PTD 1: Japanese Patent Laying-Open No. 2002-209343 [0004]
PTD 2: Japanese Patent Laying-Open No. 2010-148174 [0005] PTD 3:
Japanese Patent Laying-Open No. 2010-141966
SUMMARY OF INVENTION
Technical Problem
[0006] In the above system disclosed in Japanese Patent Laying-Open
No. 2002-209343, an interference between the electromagnetic wave
having the first frequency for data communication and the
electromagnetic wave having the second frequency for charging leads
to reduction in communication rate and/or charging efficiency. In
the above system, although the second frequency is designed to be
lower than the first frequency, if a harmonic component of the
second frequency overlaps with the first frequency, noise occurs in
the electromagnetic wave for data communication, which may lead to
communication malfunction such as reduction in communication rate
or the like.
[0007] Therefore, an object of the present invention to provide a
non-contact power reception device capable of inhibiting an
interference between power transfer and data communication and a
vehicle including the same, a non-contact power transmission
device, and a non-contact power transfer system.
Solution to Problem
[0008] According to the present invention, a non-contact power
reception device is configured to receive in a non-contact manner
power transmitted from a power transmission device, and includes a
power reception unit and a communication device. The power
reception unit is configured to receive in a non-contact manner AC
power transmitted from the power transmission device at a first
frequency. The communication device is configured to conduct
wireless communication with the power transmission device through
radio wave having a second frequency. The first frequency and the
second frequency are determined in such a way that the relationship
between the first frequency and the second frequency is a
non-integer multiple.
[0009] Preferably, the power reception unit receives in a
non-contact manner the AC power transmitted from a power
transmission unit in the power transmission device through
resonance with the power transmission unit via an electromagnetic
field.
[0010] Preferably, the second frequency is determined to be higher
than the first frequency.
[0011] Preferably, the first frequency is determined on the basis
of a transfer status of the AC power, and the second frequency is
determined in such a way that the relationship between the
determined first frequency and the second frequency is a
non-integer multiple.
[0012] Preferably, the second frequency is determined on the basis
of a communication status with the power transmission device, and
the first frequency is determined on the basis of a transfer status
of the AC power in such a range that the relationship between the
determined second frequency and the first frequency is a
non-integer multiple.
[0013] Preferably, the non-contact power reception device further
includes a modification unit configured to modify the second
frequency in such a way that the relationship between the first
frequency and the second frequency is a non-integer multiple.
[0014] Preferably, the non-contact power reception device further
includes a modification unit configured to modify the first
frequency in such a way that the relationship between the first
frequency and the second frequency is a non-integer multiple.
[0015] Preferably, the communication device is capable of selecting
one from a plurality of communication frequencies to conduct the
wireless communication with the power transmission device, and
selects a communication frequency which is a non-integer multiple
of the first frequency from the plurality of communication
frequencies as the second frequency to conduct the wireless
communication with the power transmission device.
[0016] According to the present invention, a vehicle includes any
of the non-contact power reception devices described above.
[0017] According to the present invention, a non-contact power
transmission device is configured to transmit in a non-contact
manner power to a power reception device, and includes a power
supply unit, a power transmission unit and a communication device.
The power supply unit is configured to generate AC power having a
first frequency. The power transmission unit is configured to
transmit in a non-contact manner the AC power generated by the
power supply unit to the power reception device. The communication
device is configured to conduct wireless communication with the
power reception device through radio wave having a second
frequency. The first frequency and the second frequency are
determined in such a way that the relationship between the first
frequency and the second frequency is a non-integer multiple.
[0018] Preferably, the power transmission unit transmits in a
non-contact manner the AC power to a power reception unit in the
power reception device through resonance with the power reception
unit via an electromagnetic field.
[0019] Preferably, the second frequency is determined to be higher
than the first frequency.
[0020] Preferably, the first frequency is determined on the basis
of a transfer status of the AC power, and the second frequency is
determined in such a way that the relationship between the
determined first frequency and the second frequency is a
non-integer multiple.
[0021] Preferably, the second frequency is determined on the basis
of a communication status with the power reception device, and the
first frequency is determined on the basis of a transfer status of
the AC power in such a range that the relationship between the
determined second frequency and the first frequency is a
non-integer multiple.
[0022] Preferably, the non-contact power transmission device
further includes a modification unit configured to modify the
second frequency in such a way that the relationship between the
first frequency and the second frequency is a non-integer
multiple.
[0023] Preferably, the non-contact power transmission device
further includes a modification unit configured to modify the first
frequency in such a way that the relationship between the first
frequency and the second frequency is a non-integer multiple.
[0024] Preferably, the communication device is capable of selecting
one from a plurality of communication frequencies to conduct the
wireless communication with the power reception device, and selects
a communication frequency which is a non-integer multiple of the
first frequency from the plurality of communication frequencies as
the second frequency to conduct the wireless communication with the
power reception device.
[0025] According to the present invention, a non-contact power
transfer system is configured to transfer in a non-contact manner
power from a power transmission device to a power reception device.
The power transmission device includes a power supply unit, a power
transmission unit and a first communication device. The power
supply unit is configured to generate AC power having a first
frequency. The power transmission unit is configured to transmit in
a non-contact manner the AC power generated by the power supply
unit to the power reception device. The first communication device
is configured to conduct wireless communication with the power
reception device through radio wave having a second frequency. The
power reception device includes a power reception unit and a second
communication device. The power reception unit is configured to
receive in a non-contact manner the AC power transmitted from the
power transmission unit. The second communication device is
configured to conduct wireless communication with the power
transmission device through radio wave having the second frequency.
The first frequency and the second frequency are determined in such
a way that the relationship between the first frequency and the
second frequency is a non-integer multiple.
[0026] Preferably, the power transmission unit transmits in a
non-contact manner the AC power to the power reception unit through
resonance with the power reception unit via an electromagnetic
field, and the power reception unit receives in a non-contact
manner the AC power transmitted from the power transmission unit
through resonance with the power transmission unit via an
electromagnetic field.
[0027] Preferably, the second frequency is determined to be higher
than the first frequency.
[0028] Preferably, the non-contact power transfer system further
includes a control unit. The control unit adjusts the first
frequency on the basis of a transfer status of the AC power, and
modifies the second frequency in such a way that the relationship
between the adjusted first frequency and the second frequency is a
non-integer multiple.
[0029] Preferably, the non-contact power transfer system further
includes a control unit. The control unit determines the second
frequency on the basis of a communication status with the power
transmission device, and after the determination of the second
frequency, adjusts the first frequency on the basis of a transfer
status of the AC power in such a range that the relationship
between the first frequency and the second frequency is a
non-integer multiple.
[0030] Preferably, the first and second communication devices are
capable of selecting one from a plurality of communication
frequencies to conduct the wireless communication with each other,
and select a communication frequency which is a non-integer
multiple of the first frequency from the plurality of communication
frequencies as the second frequency to conduct the wireless
communication with each other.
Advantageous Effects of Invention
[0031] In the present invention, the AC power having the first
frequency is transferred in a non-contact manner from the power
transmission device to the power reception device. Further, the
wireless communication is conducted between the power transmission
device and the power reception device through radio wave having the
second frequency. Furthermore, since the first frequency and the
second frequency are determined in such a way that the relationship
between the first frequency and the second frequency is a
non-integer multiple, neither will the harmonic component of the AC
power overlap with the radio wave for wireless communication nor
will the harmonic component of the radio wave for wireless
communication overlap with the AC power. Thereby, according to the
present invention, it is possible to inhibit the interference
between power transfer and data communication.
BRIEF DESCRIPTION OF DRAWINGS
[0032] FIG. 1 is a view illustrating a general configuration of a
non-contact power transfer system according to Embodiment 1 of the
present invention;
[0033] FIG. 2 is a view illustrating a principle of power transfer
through resonance;
[0034] FIG. 3 is a view illustrating a relationship between a
frequency and a transfer efficiency of AC power transferred from a
power transmission device to a vehicle;
[0035] FIG. 4 is a view conceptually explaining a way of
determining a power transmission frequency and a communication
frequency according to Embodiment 2;
[0036] FIG. 5 is a flowchart explaining a procedure of determining
the power transmission frequency and the communication frequency
according to Embodiment 2;
[0037] FIG. 6 is a view conceptually explaining a way of
determining a power transmission frequency and a communication
frequency according to Embodiment 3;
[0038] FIG. 7 is a flowchart explaining a procedure of determining
the power transmission frequency and the communication frequency
according to Embodiment 3; and
[0039] FIG. 8 is a view illustrating a relationship between a
frequency and a reflected power of the AC power transferred from
the power transmission device to the vehicle.
DESCRIPTION OF EMBODIMENTS
[0040] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings. It should be
noted that in the drawings the same or corresponding portions will
be given the same reference numerals, and the description thereof
will not be repeated.
Embodiment 1
[0041] FIG. 1 is a view illustrating a general configuration of a
non-contact power transfer system according to Embodiment 1 of the
present invention. With reference to FIG. 1, the non-contact power
transfer system includes a power transmission device 100, and a
vehicle 200 serving as a power reception device.
[0042] Power transmission device 100 includes a power supply unit
110, a power sensor 115, an impedance matching unit 120, an
electromagnetic induction coil 130, a resonant coil 140, a
capacitor 150, an electronic control unit (hereinafter, referred to
as "ECU") 160, and a communication device 170. Power supply unit
110 generates AC power having a prescribed frequency f1.
[0043] For example, power supply unit 110 receives power from a
system power supply (not shown) and generates AC power having
frequency f1. Frequency f1 is about 1 MHz to less than 20 MHz, for
example. Power supply unit 110 operates in response to an
instruction received from ECU 160 to generate and stop the AC power
and control power output.
[0044] Power sensor 115 detects reflected power in power supply
unit 110, and outputs the detected value to ECU 160. Note that
reflected power is power output from power supply unit 110 which is
reflected and returned to power supply unit 110. Note that power
sensor 115 can be various known sensors that can detect reflected
power in power supply unit 110. It is acceptable that power sensor
115 is further configured to be able to detect traveling-wave
power.
[0045] Impedance matching unit 120 is provided between power supply
unit 110 and electromagnetic induction coil 130, and configured to
have a variable internal impedance. Impedance matching unit 120
operates in response to an instruction received from ECU 160 to
vary impedance to match an input impedance of a resonance system
including electromagnetic induction coil 130, resonant coil 140 and
capacitor 150, and a resonant coil 210, a capacitor 220 and an
electromagnetic induction coil 230 (to be described later) which
are disposed in vehicle 200 with an output impedance of power
supply unit 110. Impedance matching unit 120, for example, may be
formed from a variable capacitor and a coil.
[0046] Electromagnetic induction coil 130 can couple with resonant
coil 140 magnetically through electromagnetic induction, and supply
AC power which is output from power supply unit 110 to resonant
coil 140. Resonant coil 140 receives power from electromagnetic
induction coil 130, and resonates via an electromagnetic field with
resonant coil 210 (to be described later) mounted in vehicle 200,
and thus transfers power in a non-contact manner to resonant coil
210 of vehicle 200. Note that resonant coil 140 is provided with
capacitor 150. Capacitor 150 is connected for example between
opposite ends of resonant coil 140.
[0047] Resonant coil 140 has its coil diameter and number of turns
appropriately designed to provide a large Q factor (for example,
Q>100) and a small coupling coefficient .kappa. on the basis of
a distance to resonant coil 210 of vehicle 200, a power
transmission frequency and the like. The power transfer by
resonance is a power transfer technique different from
electromagnetic induction which is designed to provide a small Q
factor and a large coupling coefficient .kappa..
[0048] Note that electromagnetic induction coil 130 is provided to
facilitate feeding power to resonant coil 140 from power supply
unit 110, and it is acceptable to connect power supply unit 110
directly to resonant coil 140 without disposing electromagnetic
induction coil 130. Furthermore, a stray capacitance of resonant
coil 140 may be utilized without disposing capacitor 150.
[0049] ECU 160 controls power transmission from power transmission
device 100 to vehicle 200 according to software processing through
executing a previously stored program in a central processing unit
(CPU, not shown) and/or hardware processing through a dedicated
electronic circuit. Moreover, ECU 160 controls communication with
vehicle 200 through using communication device 170 so as to
exchange with vehicle 200 information required to transmit power
from power transmission device 100 to vehicle 200.
[0050] Communication device 170 is a communication interface
configured to conduct wireless communication with vehicle 200.
Communication device 170 conducts communication with a
communication device 290 (to be described later) of vehicle 200
through using radio wave having a frequency f2 (hereinafter,
frequency f2 is also referred to as "communication frequency f2",
and meanwhile, frequency f1 of the AC power transmitted from power
transmission device 100 to vehicle 200 is also referred to as
"power transmission frequency f1" or "resonant frequency f1").
Communication frequency f2, for example, is less than 10 GHz. In
the present embodiment, communication frequency f2 and power
transmission frequency f1 are set in such a way that the
relationship between f1 and f2 is a non-integer multiple, which
will be described in detail hereinafter. The information
communicated to vehicle 200 through communication device 170
includes, for example, a power transmission starting instruction or
a power transmission stopping instruction, a power reception
efficiency or received power in vehicle 200, a voltage of the
received power, and the like.
[0051] Meanwhile, vehicle 200 serving as the power reception device
includes resonant coil 210, capacitor 220, electromagnetic
induction coil 230, a rectifier 240, a power storage device 250, a
motive power output device 260, a detector 270, an ECU 280, and a
communication device 290.
[0052] Resonant coil 210 resonates with resonant coil 140 of power
transmission device 100 via an electromagnetic field to receive
power from resonant coil 140 in a non-contact manner. Note that
resonant coil 210 is also provided with capacitor 220. Capacitor
220 is connected for example between opposite ends of resonant coil
210. Resonant coil 210 has its coil diameter, its number of turns
and the like appropriately designed to provide a large Q-factor and
a small coupling coefficient .kappa. on the basis of a distance to
resonant coil 140, a power transmission frequency and the like of
resonant coil 140 of power transmission device 100.
[0053] Electromagnetic induction coil 230 can couple with resonant
coil 210 magnetically through electromagnetic induction, and
extract the power that resonant coil 210 has received through
electromagnetic induction and output it to rectifier 240. Note that
electromagnetic induction coil 230 is provided to facilitate
extracting power from resonant coil 210, and it is acceptable that
rectifier 240 is directly connected to resonant coil 210 without
disposing electromagnetic induction coil 230. Furthermore, a stray
capacitance of resonant coil 210 may be utilized so as not to
dispose capacitor 220.
[0054] Rectifier 240 rectifies AC power extracted by
electromagnetic induction coil 230 and outputs it to power storage
device 250. Power storage device 250 is a rechargeable DC power
supply and formed of a secondary battery such as a lithium ion or
nickel hydride battery. Power storage device 250 stores power
output from rectifier 240, and also stores power generated by
motive power output device 260. Then, power storage device 250
supplies the stored power to motive power output device 260. Note
that it is acceptable to use a capacitor of a large capacitance as
power storage device 250.
[0055] Motive power output device 260 uses power stored in power
storage device 250 to generate force to drive and thus cause
vehicle 200 to travel. Although not shown in particular, motive
power output device 260 for example includes an inverter receiving
power from power storage device 250, a motor driven by the
inverter, a drive wheel driven by the motor, and the like. Note
that motive power output device 260 may include a power generator
for charging power storage device 250, and an engine that can drive
the power generator.
[0056] Detector 270 is configured to detect a state of power
received from power transmission device 100. By way of example,
detector 270 includes a voltage sensor and a current sensor,
detects a voltage V and a current I of DC power output from
rectifier 240, and outputs the detected voltage and current to ECU
280.
[0057] ECU 280 controls power reception from power transmission
device 100 according to software processing through executing a
previously stored program in a CPU (not shown) and/or hardware
processing through a dedicated electronic circuit. Moreover, ECU
280 controls communication with power transmission device 100
through using communication device 290 so as to exchange with power
transmission device 100 information required to receive power from
power transmission device 100.
[0058] Communication device 290 is a communication interface
configured to conduct wireless communication with power
transmission device 100. Communication device 290 conducts
communication with communication device 170 of power transmission
device 100 through using radio wave having frequency f2. As
mentioned above, communication frequency f2 and power transmission
frequency n are set in such a way that the relationship between f1
and f2 is a non-integer multiple.
[0059] FIG. 2 is a view illustrating a principle of power transfer
through resonance. With reference to FIG. 2, in the resonance, two
LC resonant coils (resonant coils 140 and 210) having the same
natural frequency resonate, as two tuning forks do, in an
electromagnetic field (a near field) so that one coil transfers
power to the other coil via the electromagnetic field.
[0060] Specifically, high-frequency power of 1 MHz to less than 20
MHz is fed to resonant coil 140 through electromagnetic induction
coil 130 connected to power supply unit 110. Resonant coil 140
forms an LC resonator together with capacitor 150, and resonates
via an electromagnetic field (a near field) with resonant coil 210
having the same resonant frequency as resonant coil 140. Then,
energy (power) is transferred from resonant coil 140 to resonant
coil 210 via the electromagnetic field. The energy (or power)
transferred to resonant coil 210 is extracted by electromagnetic
induction coil 230, and supplied to a load 350 following rectifier
240 (see FIG. 1).
[0061] Referring again to FIG. 1, in the non-contact power transfer
system, the frequency of the AC power transferred from resonant
coil 140 of power transmission device 100 to resonant coil 210 of
vehicle 200, namely power transmission frequency f1, and the
frequency of the radio wave for communication between communication
devices 170 and 290, namely communication frequency f2 are set in
such a way that the relationship between f1 and f2 is a non-integer
multiple. In Embodiment 1, power transmission frequency f1 and
communication frequency f2 are set in such a way that communication
frequency f2 is higher than power transmission frequency f1 and
communication frequency f2 is a non-integer multiple of power
transmission frequency f1. Thereby, a harmonic component of the AC
power transferred from resonant coil 140 to resonant coil 210 will
not overlap with the radio wave for wireless communication between
communication devices 170 and 290, and consequently, communication
malfunction such as reduction in communication rate or the like
will be inhibited.
[0062] Note that it is acceptable that power transmission frequency
f1 and communication frequency f2 are set in such a way that
communication frequency f2 is lower than power transmission
frequency f1 and power transmission frequency f1 is a non-integer
multiple of communication frequency f2. However, since the
communication rate between communication devices 170 and 290
becomes higher as communication frequency f2 increases and the
resonant system can be implemented at a lower cost as power
transmission frequency f1 decreases, as mentioned above in
Embodiment 1, power transmission frequency f1 and communication
frequency f2 are set in such a way that communication frequency f2
is higher than power transmission frequency f1 and communication
frequency f2 is a non-integer multiple of power transmission
frequency f1. For example, it is preferable that power transmission
frequency f1 and communication frequency f2 are set in such a way
that communication frequency f2 is 100 times higher than power
transmission frequency f1.
[0063] As mentioned above, in Embodiment 1, the AC power having
power transmission frequency f1 is transferred in a non-contact
manner from power transmission device 100 to vehicle 200. The
wireless communication is conducted between power transmission
device 100 and vehicle 200 through the radio wave having
communication frequency f2. Further, since power transmission
frequency f1 and communication frequency f2 are set in such a way
that the relationship therebetween is a non-integer multiple,
neither the harmonic component of the AC power will overlap with
the radio wave for wireless communication nor the harmonic
component of the radio wave for wireless communication will overlap
with the AC power. Thereby, according to Embodiment 1, it is
possible to inhibit the interference between the power transfer
from resonant coil 140 to resonant coil 210 and the wireless
communication between communication devices 170 and 290.
Embodiment 2
[0064] In Embodiment 2, power transmission frequency f1,namely the
frequency of the AC power transferred from resonant coil 140 of
power transmission device 100 to resonant coil 210 of vehicle 200,
and communication frequency f2, namely the frequency of the radio
wave for wireless communication between communication devices 170
and 290 are configured to be variable in power transmission device
100 and/or vehicle 200. Power transmission frequency f1 exerts
influence on a transfer efficiency of power transferred from
resonant coil 140 of power transmission device 100 to resonant coil
210 of vehicle 200.
[0065] FIG. 3 is a view illustrating the relationship between the
frequency and the transfer efficiency of AC power transferred from
power transmission device 100 to vehicle 200. With reference to
FIG. 3, the transfer efficiency reaches the maximum at a certain
frequency and decreases at frequencies deviated from the certain
frequency.
[0066] Thus, in Embodiment 2, power transmission frequency f1 is
firstly adjusted on the basis of a transfer status (such as a power
reception efficiency of vehicle 200) from power transmission device
100 to vehicle 200. Specifically, power transmission frequency f1
is firstly adjusted to maximize the power transfer efficiency.
After the adjustment of power transmission frequency f1 is
finished, communication frequency f2 is determined in such a way
that communication frequency f2 is a non-integer multiple of power
transmission frequency f1. Specifically, for example, a plurality
of communication channels of mutually different frequencies are
prepared in advance, and a communication channel having
communication frequency f2 which is a non-integer multiple of power
transmission frequency f1 is selected.
[0067] FIG. 4 is a view conceptually explaining a way of
determining power transmission frequency f1 and communication
frequency f2 according to Embodiment 2. With reference to FIG. 4,
in Embodiment 2, power transmission frequency f1 is adjusted so as
to maximize the transfer efficiency of power transmitted from power
transmission device 100 to vehicle 200, and thus, power
transmission frequency f1 is determined at first.
[0068] After the determination of power transmission frequency
f1,whether or not communication frequency f2 is an integer multiple
of power transmission frequency f1 is determined. Suppose that
communication frequency f2 is f2_1 and f2_1 is an integer multiple
of power transmission frequency f1, in other words, in the case
where communication frequency f2 overlaps with the harmonic
component of the AC power which is being transmitted, communication
frequency f2 is modified to f2_2 which is a non-integer multiple of
power transmission frequency f1.
[0069] The general configuration of the non-contact power transfer
system according to Embodiment 2 is the same as the non-contact
power transfer system according to Embodiment 1 illustrated in FIG.
1.
[0070] FIG. 5 is a flowchart explaining a procedure of determining
power transmission frequency f1 and communication frequency f2
according to Embodiment 2. With reference to FIG. 5 along with FIG.
1, communication is firstly established between communication
device 170 of transmission device 100 and communication device 290
of vehicle 200 (step S10). Here, communication frequency f2 is
temporarily set to a predetermined initial value. Then, the power
transfer from power transmission device 100 to vehicle 200 is
started, and the transfer efficiency of power transmitted from
power transmission device 100 to vehicle 200 is calculated (step
S20). By way of example, the power reception efficiency (the ratio
of the power received by vehicle 200 relative to the power
transmitted from power transmission device 100) of vehicle 200 is
calculated as the transfer efficiency. The calculation of the
transfer efficiency may be performed in ECU 160 of power
transmission device 100 or may be performed in ECU 280 of vehicle
200. In the case where the transfer efficiency is calculated in ECU
160 of power transmission device 100, the detection value of the
power received is sent from vehicle 200 to power transmission
device 100 by using communication devices 170 and 290. In the case
where the transfer efficiency is calculated in ECU 280 of vehicle
200, the value of the power transmitted is sent from power
transmission device 100 to vehicle 200 by using communication
devices 170 and 290.
[0071] Thereafter, power transmission frequency f1 is adjusted on
the basis of the transfer efficiency calculated in step S20 (step
S30). That is, as illustrated in FIG. 3, power transmission
frequency f1 is adjusted to maximize the transfer efficiency. The
adjustment of power transmission frequency f1 is performed by ECU
160 through the way of controlling power supply unit 110 which is
configured to be capable of modifying the frequency of AC power on
the basis of an instruction from ECU 160. In addition, the
adjustment of power transmission frequency f1 may be performed in
ECU 280 of vehicle 200 substantially in such a way that a frequency
modification instruction for power supply unit 110 is generated in
ECU 280 of vehicle 200 on the basis of the transfer efficiency, and
the generated instruction is transmitted to power transmission
device 100 through communication devices 290 and 170.
[0072] After the adjustment of power transmission frequency f1 is
finished, whether or not communication frequency f2 is an integer
multiple of power transmission frequency f1 is determined (step
S40). Communication frequency f2 is not necessarily to be a
complete integer multiple of power transmission frequency f1,and
communication frequency f2 is determined to be an integer multiple
of power transmission frequency f1 in the case where an integer
multiple of power transmission frequency f1 is contained in a band
width offered to communication frequency f2 without causing
communication malfunction. Although it has been described that
power transmission frequency f1 is a frequency of the AC power
generated by power supply unit 110 of power transmission device 100
and the determination process of step S40 is performed in ECU 160
of power transmission device 100, it is acceptable that the value
of power transmission frequency f1 is sent to vehicle 200 and the
above determination process may be performed in ECU 280 of vehicle
200.
[0073] Subsequently, if it is determined that communication
frequency f2 is an integer multiple of power transmission frequency
f1 in step S40 (YES in step S40), communication frequency f2 is
modified in such a way that communication frequency f2 is a
non-integer multiple of power transmission frequency f1 (step 550).
For example, the current communication channel between
communication devices 170 and 290 is switched by ECUs 160 and 280
to another communication channel having a frequency which is a
non-integer multiple of power transmission frequency f1.
[0074] On the other hand, if it is determined that communication
frequency f2 is a non-integer multiple of power transmission
frequency f1 in step S40 (NO in step S40), the procedure proceeds
to step S60 without executing the process in step 550.
[0075] As mentioned above, in Embodiment 2, power transmission
frequency f1 is adjusted firstly on the basis of the transfer
status of power from power transmission device 100 to vehicle 200,
and after the adjustment of power transmission frequency f1 is
finished, communication frequency f2 is selected in such a way that
communication frequency f2 is a non-integer multiple of power
transmission frequency f1. Thus, according to Embodiment 2, it is
possible to inhibit the interference between the power transfer and
the wireless communication between communication devices 170 and
290 while achieving a high transfer efficiency in the power
transfer from resonant coil 140 to resonant coil 210.
Embodiment 3
[0076] In Embodiment 2, power transmission frequency f1 is adjusted
firstly on the basis of the transfer status from power transmission
device 100 to vehicle 200, and thereafter, communication frequency
f2 is selected in such a way that communication frequency f2 is a
non-integer multiple of power transmission frequency
[0077] Meanwhile, the degree of freedom of selecting communication
frequency f2 may be restricted greatly by communication standards
or usage conditions of radio wave. Thus, in Embodiment 3,
communication frequency f2 is selected on the basis of the
communication status between communication devices 170 and 290, and
after communication frequency f2 is determined, power transmission
frequency f1 is adjusted in such way that communication frequency
f2 is a non-integer multiple of power transmission frequency f1
while considering the transfer status of power.
[0078] FIG. 6 is a view conceptually explaining a way of
determining power transmission frequency f1 and communication
frequency f2 according to Embodiment 3. With reference to FIG. 6,
in Embodiment 3, communication frequency f2 is selected on the
basis of the communication status between communication devices 170
and 290, and thus, communication frequency f2 is determined at
first. Here, communication frequency f2 is assumed to be fixed at
f2_2.
[0079] Then, power transmission frequency f1 is adjusted to
maximize the transfer efficiency of the power transmitted from
power transmission device 100 to vehicle 200. Here, power
transmission frequency f1 is adjusted to f1_1, and in the case
where communication frequency f2 (f2_2) is an integer multiple of
power transmission frequency f1 (f1_1), in other words, when
communication frequency f2 overlaps with the harmonic component of
the AC power which is being transmitted, then, power transmission
frequency f1 is modified from f1_1 to f1_2 in such a way that
communication frequency f2 is a non-integer multiple of power
transmission frequency f1. In addition, in order to prevent the
transfer efficiency from being degraded significantly due to the
modification of power transmission frequency f1, the modification
amount of power transmission frequency f1 is limited to the
minimum.
[0080] The general configuration of the non-contact power transfer
system according to Embodiment 3 is the same as the non-contact
power transfer system according to Embodiment 1 illustrated in FIG.
1.
[0081] FIG. 7 is a flowchart explaining a procedure of determining
power transmission frequency f1 and communication frequency f2
according to Embodiment 3. With reference to FIG. 7 along with FIG.
1, communication is firstly established between communication
device 170 of transmission device 100 and communication device 290
of vehicle 200 (step S110). Then, the communication status between
communication devices 170 and 290 is confirmed by ECU 160 and/or
ECU 280 (step S120). For example, the quality of the communication
status is confirmed according to the determination of whether or
not cross talk is occurring, whether or not the communication is
being conducted at a predetermined communication rate or the
like.
[0082] If it is determined that the communication status is in a
bad quality in step S120 (NO in step S120), communication frequency
f2 is modified (step S130). For example, the currently selected
communication channel between communication devices 170 and 290 is
switched by ECUs 160 and 280 to another communication channel.
Thereafter, the procedure returns to step S120.
[0083] If it is determined that the communication status is in a
good quality in step S120 (YES in step S120), the power
transmission from power transmission device 100 to vehicle 200 is
started, and the transfer efficiency of power transmitted from
power transmission device 100 to vehicle 200 is calculated (step
S140). Thereafter, power transmission frequency f1 is adjusted on
the basis of the calculated transfer efficiency (step S150). After
the adjustment of power transmission frequency f1 is finished,
whether or not communication frequency f2 is an integer multiple of
power transmission frequency f1 is determined (step S160). Since
the respective process of steps S140, S150 and S160 is the same as
the respective one of steps S20, S30 and S40 illustrated in FIG. 5,
the descriptions thereof will not be repeated.
[0084] If it is determined that communication frequency f2 is an
integer multiple of power transmission frequency fi in step S160
(YES in step S160), power transmission frequency f1 is modified in
such a way that communication frequency f2 is a non-integer
multiple of power transmission frequency f1 while considering the
power transfer status (step S170). Specifically, power transmission
frequency f1 is modified in such a way that communication frequency
f2 is a non-integer multiple of power transmission frequency f1
while limiting the modification amount of power transmission
frequency f1 to the minimum so as to prevent the transfer
efficiency from being degraded significantly due to the
modification of power transmission frequency f1. The modification
of power transmission frequency f1 is performed by ECU 160 through
the way of controlling power supply unit 110. In addition, by
generating the frequency modification instruction for power supply
unit 110 in ECU 280 of vehicle 200 and transmitting it to power
transmission device 100, the modification of power transmission
frequency f1 may be performed in ECU 280 of vehicle 200
substantially.
[0085] On the other hand, if it is determined that communication
frequency f2 is a non-integer multiple of power transmission
frequency f1 in step S160 (NO in step S160), the procedure proceeds
to step S180 without executing the process in step S170.
[0086] As mentioned above, in Embodiment 3, communication frequency
f2 is selected on the basis of the communication status between
communication devices 170 and 290, and after the determination of
communication frequency f2, power transmission frequency f1 is
adjusted in such a way that communication frequency f2 is a
non-integer multiple of power transmission frequency f1 while
considering the power transfer status. Thus, according to
Embodiment 3, even in the case where the degree of freedom in
selecting communication frequency f2 is limited, it is possible to
inhibit the interference between the power transfer and the
wireless communication between communication devices 170 and 290
while achieving a high transfer efficiency.
Embodiment 4
[0087] With reference to FIG. 1 again, the non-contact power
transfer system according to Embodiment 4 includes communication
devices 170A and 290A in place of communication devices 170 and
290, respectively. Communication devices 170A and 290A are
configured to be able to communicate with each other by selecting
one communication frequency from a plurality of communication
frequencies. Thus, communication devices 170A and 290A select from
the plurality of communication frequencies a communication
frequency which is a non-integer multiple of resonant frequency f1
as communication frequency f2 to communicate with each other.
[0088] Note that the selection of the communication frequency in
communication device 170A may be performed by ECU 160 through
controlling communication device 170A on the basis of resonant
frequency f1. Similarly, the selection of the communication
frequency in communication device 290A may be performed by ECU 280
through controlling communication device 290A on the basis of
resonant frequency f1.
[0089] Similarly, according to Embodiment 4, it is possible to
inhibit the interference between the power transfer from resonant
coil 140 to resonant coil 210 and the wireless communication
between communication devices 170A and 290A.
[0090] In Embodiment 2 and Embodiment 3 described in the above,
power transmission frequency f1 is adjusted on the basis of the
transfer efficiency of power transmitted from power transmission
device 100 to vehicle 200. However, the parameter used to adjust
power transmission frequency f1 is not limited to the transfer
efficiency. For example, it is possible to adjust power
transmission frequency f1 on the basis of a reflected power
detected by power sensor 115 disposed in power transmission device
100.
[0091] FIG. 8 is a view illustrating a relationship between a
frequency and a reflected power of the AC power transferred from
power transmission device 100 to vehicle 200. With reference to
FIG. 8, the reflected power reaches minimized at a certain
frequency and increases at frequencies deviated from the certain
frequency. Thus, it is acceptable to adjust power transmission
frequency f1 so that the reflected power which is detected by power
sensor 115 becomes minimum.
[0092] In each embodiment mentioned in the above, the power is
transferred from power transmission device 100 to vehicle 200
through using a pair of resonant coils 140 and 210; however, in
place of each coil-shaped resonant coil 140 or 210, it is
acceptable to use a rod-shaped or a fishbone-shaped antenna, or to
use a high dielectric disk made of a high dielectric material.
[0093] In the above, impedance matching unit 120 is disposed in
power transmission device 100 to adjust the impedance of the
resonance system. However, it is acceptable that in place of
impedance matching unit 120, a DC/DC converter is disposed
posterior to rectifier 240 in vehicle 200, and the impedance of the
resonance system is adjusted through controlling the DC/DC
converter.
[0094] In the above, it is described that resonant coils 140 and
210 are designed so that each of resonant coils 140 and 210 has a
large Q factor and a small coupling coefficient .kappa., and the
power is transferred from resonant coil 140 to resonant coil 210
through the resonance between resonant coils 140 and 210. However,
the present invention is also applicable to such a system that
transfers power from a power transmission device to a vehicle
through electromagnetic induction. Specifically, in the non-contact
power transfer system illustrated in FIG. 1, electromagnetic
induction coil 130 and resonant coil 140 are formed by one coil,
resonant coil 210 and electromagnetic induction coil 230 are formed
by one coil, and each coil is designed to provide a small Q factor
and a large coupling coefficient .kappa. so as to transfer power
from the power transmission device to the vehicle through
electromagnetic induction. However, in general, the power being
transmitted through resonance has a power transmission frequency
higher than the power transmission through electromagnetic
induction, and thus, the difference between the communication
frequency and power transmission frequency becomes smaller, which
makes the interference between the communication frequency and the
power transmission frequency become significant. Therefore,
although the present invention is applicable to the power
transmission through electromagnetic induction, it is suitable for
the power transmission through resonance.
[0095] In the above, resonant coil 140 and capacitor 150 constitute
one example of "power transmission unit" in the present invention,
and resonant coil 210 and capacitor 220 constitute one example of
"power reception unit" in the present invention.
[0096] It should be understood that the embodiments disclosed
herein have been presented for the purpose of illustration and
description but not limited in all aspects. It is intended that the
scope of the present invention is not limited to the description
above but defined by the scope of the claims and encompasses all
modifications equivalent in meaning and scope to the claims.
REFERENCE SIGNS LIST
[0097] 100: power transmission device; 110: power supply unit; 115:
power sensor; 120: impedance matching unit; 130, 230:
electromagnetic induction coil; 140, 210: resonant coil; 150, 220:
capacitor; 160, 280: ECU; 170, 170A, 290, 290A: communication
device; 200; vehicle; 240: rectifier; 250: power storage device;
260: motive power output device; 350: load
* * * * *